1. Field
The invention has to do with agricultural sprinkler irrigation systems as customarily employed for movement successively from place to place along a field across which the sprinkler pipe of the system extends, thereby blanketing the field with sprinkler-provided water.
2. State of the Art
Sprinkler irrigation systems of the type concerned are widely used to supply needed irrigation water in a manner simulating natural rainfall, as contrasted with time-honored irrigation ditch systems for supplying running water directly to the roots of growing plants from furrows leading from supply ditches and extending between crop rows.
Such sprinkler irrigation systems customarily include a mover unit having traction wheels driven from an internal combustion engine, an electric motor, or hydraulic motor mounted on the unit. The mover unit is located centrally or near centrally of wheel-supported, end-to-end-coupled, sprinkler pipe sections extending across the field to be irrigated, and is reached only after a long walk across the field. To avoid frequent long walks by the person in charge of the system, various remote control arrangements have been provided for starting and stopping the engine or motor on the mover unit, see for example, Vollmer U.S. Pat. No. 4,016,902 issued Apr. 12, 1977, for "End-Control Agricultural sprinkler Irrigation Systems" and Cornelius U.S. Pat. No. 3,978,882 issued Sept. 7, 1976 for "Mover Unit for Irrigation Line".
Electric power is particularly advantageous, since remote control is achieved easily at an end of the coupled pipe sections by merely plugging into and out of an electrical supply line at successive locations along the extent thereof at a side of the field. However, since an electrical cord or cable must extend along the rotating sprinkler pipe sections to electrical connections with the electric motor or motors utilized to drive the mover unit of the system, a slip ring is normally required for this purpose if end control is to be achieved. This causes complications, both in construction and maintenance of the system. The only electrical system known to applicant is that produced by Elmer Funk, the patentee of U.S. Pat. No. 3,318,531, issued May 9, 1967 for "Irrigation Pipe Propelling Apparatus". Although the patent shows and describes a system powered by an electrical generator aboard a tractor that is movable with the system from irrigating location to irrigating location along the length of the main water-supply pipe, and an electric motor driving a pinion gear which is in mesh and adapted to travel around the circumference of a stationary reaction or bull gear to effect rotation of the sectional irrigation pipe and the traction wheels supporting same in the field, the electric motor and speed reduction gear box of such arrangement traveling around the reaction gear along with the drive pinion, and there being a slip ring connection between the generator and the motor, in actual practice this is not used. Rather, the electric motor is mounted so as to be stationary, and the reaction gear is rigidly fixed to the sectional irrigation pipe so as to be driven by the pinion and, in turn, rotate the pipe. A slip ring connection is provided between the pipe-carried electric cord or cable and the electric motor, so that plug-in connections can be made with a source of electric power at convenient locations along a side of the field as the system is moved from place to place successively.